A vacuum chamber machine is known from CN 202783871 U disclosing the manual opening and closing of a chamber lid, where a spring is provided for weight relief for the chamber lid. If the tension spring fractures, then the operator would only notice this when opening the chamber lid.
Vacuum chamber machines marketed by the Applicant under the name C700 are known in the market as having a motor-driven chamber lid pivot motion. Tension springs are provided for weight relief for the chamber lid because such chamber machines can, due to their sometimes very large dimensions, have a chamber lid with a weight of up to 200 kg. Such motor-driven chamber lids are provided with a protective frame which is configured to perform a relative motion during closing motion towards the chamber lid when, for example, a body part of the operator is located within the chamber machine in the region of the chamber lid. The relative movement of the protective frame relative to the chamber lid is detected by sensors and the controller stops the motorized chamber lid drive, thereby preventing injury. In this, the chamber lid must come to a standstill within the protective frame. For this purpose, it is necessary to deplete the kinetic energy of the mass of the chamber lid about a pivot point of the chamber lid within a respective rotational angle. For this, several tension springs are provided to support the motorized chamber lid drive or to provide a weight counterbalance. Should during operation a spring fracture occur, this can hardly be detected by the operator because the chamber lid usually still automatically opens and closes again. In case of danger, in which the protective frame triggers, the chamber lid is less supported and the chamber lid can no longer be brought to a standstill by the motor in time to prevent injury.